While Americans savored the last moments of summer this Labor Day weekend, the U.S. military was busy overseas as warplanes conducted strikes in six countries in a flurry of attacks. The bombing runs across Asia, Africa and the Middle East spotlighted the diffuse terrorist threats that have persisted into the final days of the Obama presidency — conflicts that the next president is now certain to inherit.

In Iraq and Syria, between Saturday and Monday, the United States conducted about 45 strikes against Islamic State targets. On the other side of the Mediterranean, in the Libyan city of Sirte, U.S. forces also hit fighters with the militant group. On Sunday in Yemen, a U.S. drone strike killed six suspected members of ­al-Qaeda in the Arabian Peninsula. The following day, just across the Gulf of Aden in Somalia, the Pentagon targeted al-Shabab, another group aligned with ­al-Qaeda. The military also conducted several counterterrorism strikes over the weekend in Afghanistan, where the Taliban and the Islamic State are on the offensive.

Militants in each of those countries have been attacked before, but the convergence of so many strikes on so many fronts in such a short period served as a reminder of the endurance and geographic spread of al-Qaeda and its mutations.

“This administration really wanted to end these wars,” said Paul Scharre, a former Army Ranger and Pentagon official now at the Center for a New American Security. “Now, we’ve got U.S. combat operations on multiple fronts and we’re dropping bombs in six countries. That’s just the unfortunate reality of the terrorism threat today.”

In meeting those threats, Obama has sought to limit the large-scale deployments of the past, instead relying on air power, including drones; isolated Special Operations raids; and support for foreign forces.

The Department of Defense released footage on Aug. 24 that it said showed coalition airstrikes on Islamic State targets in Iraq. The video shows strikes on fighting positions concentrated near Sultan Abdallah on Aug. 9 (Reuters)

But militant groups have defied eight years of these sustained counterterrorism efforts.

Nowhere are the unexpected turns of Obama’s foreign-policy record more visible than in Iraq, where thousands of U.S. troops returned after the 2011 withdrawal to support local forces’ battle against the Islamic State. A smaller Special Operations force is based in northern Iraq, responsible for hunting down militant leaders.

U.S. warplanes conducted about 20 strikes in Iraq over the weekend, largely centered in northern Nineveh province and Mosul, the strategic city that local forces hope to recapture from the Islamic State this year. But there were also strikes in Iraq’s western Anbar province, which has largely been retaken from the Islamic State. That suggests that some militant cells linger in areas cleared by the Iraqi army.

The resumption of U.S. combat activities in Iraq in 2014 represented not only the extent of Iraq’s unsolved problems after the American departure, but also the power of the war in neighboring Syria to destabilize areas once considered secure.

In Syria over the weekend, more than 25 strikes hit targets across the country’s north and east, highlighting the Pentagon focus on the Islamic State’s de facto capital of Raqqa. While U.S. officials hope that friendly local forces can encircle the city, the path ahead is complicated by the fractured, internationalized nature of the conflict in Syria.

In Libya, as in Iraq and Syria, local ground forces are the key to the U.S. goal of defeating the Islamic State. Over the weekend, U.S. planes pounded at least 20 Islamic State targets in the coastal city of Sirte, where militia forces have struggled to defeat a small but resilient band of militants dug in by the sea.

After months of watching a powerful Islamic State affiliate expand, U.S. Africa Command launched an air campaign over Sirte last month. For U.S. officials, the air power is critical to help local forces disrupt militants’ ability to plot external attacks. For critics of Obama, the need for such an intervention is proof of the president’s failure in Libya following his 2011 intervention, which sought to limit American involvement.

“It’s certainly the case if you look over the last 16 years, there are times when we have gone in way too heavy, and that’s caused problems, and times when we’ve gone in too light, and that has caused problems,” said William F. Wechsler, a former Pentagon official who oversaw U.S. Special Operations activities.

“What you’ve seen at the end of the Obama administration is a determination that there is this . . . middle ground that both allows us to meet our counterterrorism objectives but also support our allies who are doing fighting on the ground,” he said.

The United States now faces a test of its ability to do just that in Afghanistan, where local forces are struggling to contain a startling comeback by the Taliban. Almost 10,000 U.S. service members are part of a dual mission to support the Afghan army and conduct counterterrorism operations against both al-Qaeda and militants loyal to the Islamic State.

Beyond those ongoing conflicts, the Pentagon has kept up its lower-intensity operations against militants in more far-flung places, often in a fashion that is shielded from public view.

On Sunday, in Yemen’s central Shabwah province, a U.S. drone fired at a group of suspected members of al-Qaeda in the Arabian Peninsula, killing six, according to U.S. Central Command. It was the latest in a recent series of attacks that seeks to ensure that AQAP, once the most fearsome al-Qaeda affiliate, cannot rebound amid the Yemeni civil war.

The United States has sought to limit its military involvement in Yemen, keeping a small counterterrorism presence close to the coast and providing logistical support to Saudi Arabia’s bombing campaign against Houthi rebels.

The Pentagon on Monday also conducted a pair of strikes in Tortoroow, Somalia, in defense of African peacekeeping forces that are operating with U.S. support there. According to U.S. African Command, the African forces had been attacked by a large group of al-Shabab fighters.

While the breadth of ongoing U.S. combat operations may appear to be a step back from the Obama administration’s earliest national-security goals, Scharre said the bombing was an appropriate response to an array of security threats, one that might be sustained over time in the same way that the United States has committed to long-term military presences in places such as Germany and South Korea.

“I think the goal of getting to zero U.S. involvement was always just the wrong metric,” he said. “The goal was to get to the place where U.S. involvement is commensurate with our interests.”

Missy Ryan writes about the Pentagon, military issues and national security for The Washington Post. She joined The Post in 2014 from Reuters, where she reported on U.S. national security and foreign policy issues. She has reported from Iraq, Egypt, Libya, Lebanon, Yemen, Afghanistan, Pakistan, Mexico, Peru, Argentina and Chile.